Plant friends and foes

Periwinkle and Other Invasive Evergreen Groundcovers

Terry Bonace

Patches of periwinkle (Vinca minor) grow almost everywhere in Beverly Shores. Low-growing periwinkle is easy to miss but it begins to stand out as the leaves of other plants begin to fall. Periwinkle at one time was extremely popular as a ground cover because it grows and spreads so reliably, even in heavy shade, and has a sprinkling of pretty flowers in spring. It also is evergreen so it provides some winter interest. Many a wooded lot where the house no longer stands stills has a sizeable, ever expanding patch of periwinkle, outlasting the house by many years

Periwinkle

Periwinkle was first introduced as an ornamental form Europe in the 1700s. So well-known is this plant and its flower that its name is used to describe a shade of violet-blue. In Ohio, however, we always called the plant “myrtle.” As a very young gardener, I was taken in by a nursery advertisement for the novel name, “periwinkle,” promoted with beautiful illustrations of shiny, green leaves and a large, violet-blue flower, and sold for a very cheap price. Imagine my dismay when the periwinkle arrived and I learned that it was only the very humble myrtle. And this for the nickels and dimes I scraped together from various odd jobs!

Like so many of our fast growing and spreading ornamentals, periwinkle is a major problem in natural areas throughout the eastern United States. The Invasive Plant Species Assessment Working Group, reports escaped populations of periwinkle in every county in the state of Indiana. It grows so densely that few native plants can compete with it. Since the Indiana Dunes area is renowned for its plant diversity, and because so many creatures, from insects to mammals, rely on these natives, we should do everything in our power to maintain this diversity, starting in our own backyards.

Don’t confuse glossy buckthorn with our beautiful and less common native, winterberry (Ilex verticillata) to which it bears a superficial resemblance. Winterberry has very fine teeth on the leaves and the fruit appears in bright red clusters close along the stem. Winterberry is a prized native, good for birds and wildlife, and pleasing to the eye.

If you have periwinkle and want to get rid of it, try digging it up. Though a time consuming chore, it can be accomplished with perseverance. Otherwise, kill it with Roundup herbicide (glyphosate). But because periwinkle’s glossy leaves shed water, mow the plant down before applying the herbicide. Some repeat applications may be necessary. Remember to read and comply with all label directions

There are a number of other evergreen groundcovers that are problems in some parts of the United States though not necessarily yet in the Indiana Dunes region. Think twice before incorporating them into your landscaping. Wintercreeper (Euonymus fortunei), like oriental bittersweet, can climb over trees and rocks and is very tolerant of a wide range of habitats. English ivy (Hedera helix) is very aggressive and difficult to combat, so much so that it can kill the trees that it entwines. Pachysandra (Pachysandra terminalis) is a very tolerant evergreen ground creeper that spreads by rhizomes. I know from personal experience if it is at all happy in its surroundings, it will spread like wildfire. Happiness for it means a little shade, a little organic material and a little moisture, a common combination in Beverly Shores.

Wild Ginger

Invasive groundcovers that are not evergreen will be a topic for a separate article, as there are a great number of them. I will also write about native replacements for both evergreen and non-evergreen groundcovers. However, for those anxious to research a few potential substitutes, consider partridgeberry (Mitchella repens), a delicate and lovely ground creeper with bright red berries and a nice central vein in its tiny leaves. Partridgeberry commonly grows in our native woods nearby. Bearberry (Arctostaphylos uva-ursi) is another evergreen creeper with small leaves and berries, but it grows in the sandier, sunnier areas of the dunes. It would also make a lovely ground cover. Wild ginger (Asarum canadense) is a non-evergreen native groundcover with which I have had great success in a number of harsh environments, including dry sandy shade. Wild ginger has pretty, heart-shaped leaves that form a dense ground cove

The Environmental Restoration Group (ERG) will be glad to help identify plants for you and make suggestions for removal and for native replacements. Don’t hesitate to contact Terry Bonace (tbonace@gmail.com), Candice Smith (cmsmith2@umail.iu.edu), or Bill Schaudt (blschaudt2@gmail.com) for assistance.

Beverly Shores Environmental Restoration Group,
P.O. Box 667, Beverly Shores, IN 46301